In an etching process of a manufacturing process of a semiconductor device or a flat panel display (FPD), a film on a surface of a substrate to be processed (a semiconductor wafer, a glass substrate or the like) is processed in a desired circuit pattern by using as a mask a resist pattern formed by a lithography technique. Conventionally, a capacitively coupled plasma etching apparatus has been widely used for single-wafer etching.
Generally, in a capacitively coupled plasma etching apparatus, an upper electrode and a lower electrode are arranged in parallel in a vacuum processing chamber, and a substrate to be processed is mounted on the lower electrode. When a radio frequency power is applied between the electrodes, a plasma is generated by a high frequency discharge between the electrodes. Accordingly, the surface of the substrate is etched in a desired pattern by radicals or ions in the plasma.
In a currently most advanced LSI process, an ArF excimer laser exposure technique is used for photolithography, and a chemically amplified resist (ArF resist) suitable for a wavelength (193 nm) of an ArF excimer laser beam is used as a resist. The ArF resist has high sensitivity and high resolution, but provides poor plasma resistance or etching resistance. Further, the patterning is performed in an ultra-fine size, so that resist pattern collapse, surface roughness, or uneven pattern sidewall can occur during plasma etching. Therefore, zigzag or uneven deformation such as poor LER (Line Edge Roughness), LWR (Line Width Roughness) or the like may be caused.
Conventionally, as for a technique for improving etching resistance of an ArF resist, there is known a method for modifying a resist by electron beam irradiation, UV irradiation, H2 or HBr plasma irradiation, ion beam irradiation or the like.
However, the conventional resist modification method requires a processing vessel (chamber) exclusively, thereby resulting in that a cost of apparatus increases while a throughput of the apparatus decreases. If the electron beam irradiation method, the UV irradiation method or the ion beam irradiation method is used before an exposure to light, light transmissivity of the resist pattern is changed because of the resist film quality change, thereby deteriorating the exposure performance. If the ion beam irradiation method is used after an exposure to light, the resist pattern can be easily damaged by an ion impact. If the electron beam irradiation method or the UV irradiation method is used, taper-shaped shrinkage deformation or CD (critical dimension) variation can occur easily in the resist pattern. Moreover, the H2 or HBr plasma irradiation method is disadvantageous in that it is difficult to reproduce the process due to residual hydrogen in the chamber, and also in that operation stability or production yield is poor.